1. Field of the Invention
This invention relates generally to leg or foot orthopedics and more particularly to a composite orthotic material and a method of manufacture for a custom orthotic device.
2. Background of the Invention
Orthotics, being a branch of mechanical and medical science dealing with bracing or straightening weak or ineffective joints or muscles, involves the custom manufacture of orthotic devices to be worn inside a patient's shoes as a brace or support to help minimize physical discomfort for patients suffering from structural deficiencies in their feet or legs. In the past two decades, two types of light-weight materials have been developed and used in orthotics.
The first type involves a number of thermoplastics that can easily be formed into orthoses by heat. Materials of this type are limited in that they have relatively low tensile and flexural strength. They also have a low modulus of elasticity and poor fatigue resistance. Furthermore, their use is limited to thick sections of orthotic devices because of a stiffness requirement that limits their use in conventional shoes. In addition, they suffer from time-dependent problems such as creep, which renders them ineffective for correcting structural deficiencies. Still further, their strength-to-weight ratio is low.
The second type of material involves a number of advanced composites that have recently been developed to overcome some of the limitations of thermoplastics. Glass and graphite fibers have been introduced into the construction of orthotics in order to provide effective reinforcement. This yielded significant improvement in mechanical properties, including strength-to-weight ratio, flexural strength, modulus, and creep resistance. This also made it possible to use thinner orthotics and to achieve better corrective action than provided by thermoplastics. However, many limitations still exist in that these composites are hard and brittle and have relatively low toughness and impact resistance. Reinforcing fibers used in these composites are usually introduced in one direction, longitudinally, causing the orthotic to be weak in the transverse direction. As a result, orthotic devices made in this way are known to fracture catastrophically and not gradually, and have poor capacity for damping vibrations.
The foregoing illustrates limitations known to exist in present devices. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided, including features more fully disclosed hereinafter.